Method of moistening and wetting out leather and dried hides



Patented Mar. 3, i931 HES? AVAiLABLE COP;

Uttllttiit FATENT @FFEQEE FRIEDRICH POSPIEGH, 0E DRESDEN, GERMANY, ASSIGNOR 'IO CHEMISCHE FABRIK.

PO'IT 85 ('10., 0F DRESDEN, GER-MANY METHOD OF MOISTENING IiiNI) WETTING OUT LEATHER AND DRIED RIDES No Drawing. App1ication filed August 26, 1927, Serial No. 215,763, and in Germany August 30, 1926.

It is almost impossible to thoroughly wet out leather which has been dried and make the same moist and pliant. This is especially true in the case of chrome-leather. Acids will more or less eifect a de-tanning of the leather, which hardly can be remedied again. Also the grains and the color of the leather will suffer by the treatment with an acid. If alkalies are employed the leather will become over-neutralized, and will lose its soft leather-like feeling and acquire a metallic stiffness after being dried. Further, neither the treatment with acids nor the treatment with alkalies will make it possible to moisten chromeleather thoroughly. This may be observed for instance by treating the moistened leather with fats in which case the fatty matter Will remain on the surface of the hide and not penetrate into the interior of the same.

Also when tanned leather is subjected to a softening treatment portions of the same remain dry. If acids are applied the leather acquires a stiff unleather-like feeling; on the other hand alkalies effect a reddening of the color. Also, the soaking or moistening of alumed or kid leather is connected with great technical difficulties. Usually a so-called fulling-mill is employed, which comprises one or more hammers by means of which the leather is beaten, until it has become thoroughly soaked. Ammonia containing substances are frequently added. This method is however Very defective in technical respects, since too much of the tanning material (alum, flour) is removed from the leather and the leather is often damaged during the hammering.

According to the present invention the above named drawbacks are avoided by moistening or soaking the leather in the presence of wetting agents. As such agents aromatic sulphonic acids, or the salts of such acids, may be mentioned as very advantageous for the purpose.

Especially advantageous are sulphonic acids of compounds which are obtained by condensing naphthalene or the ring substitution products of naphthalene in the presence of condensation and oxidation-agents with alcohols of the aliphatic series, containing more than two carbon atoms. These products are probably sulphonic acids of alkylated aromatic compounds of the naphthalene series. It is also possible to use the salts of such compounds.

Compounds of the above mentioned kind are obtained for instance, by condensing naphthalene-monoor poly-sulphonic acids at approximately 100 C. in the presence of sulphuric acid with propyl alcohols, butyl alcohols, cyclo-hexanol or other higher alcohols. The surplus of sulphuric acid is removed from the condensation products in the usual way. Gther compounds, which can be used for producing products of the above named kind are: other poly-nuclear hydrocarbons or sulpho-acids of such hydrocarbons, as for instance, phenanthrene or anthracene-sulphonic acids, and also substitution products such as chloro-naphthalenesulphonic acid, naphthol-sulphonic acids and the like. Instead of the higher alcohols, the corresponding olefines and, in general, aliphatic and cyclic olefines, as for instance, tetra-hydrobenzol, may be employed.

The same method may be employed for moistening dried hides. When such hides are soaked for a longer time, especially during hot seasons, skin substance is lost on account of septics in the water or in the hide. n

Alkalies are often employed to accelerate the moistening, but also alkalies may damage the hides by removing skin substance and swelling the hides. According to this invention, however, these drawbacks are avoided by employing the substances named above.

Example 1.-100 kg. of dried hides are placed in a pit containing about 250 liters of water and 0.5 kg. of a product obtained by condensing naphthalene or its ring substitution products'in the presence of condensationand oxidation-agents with alcohols of the aliphatic series, which contain more than two carbon atoms. After 24 hours the hides are wetted out through and through, so that they can be transferred directly to the lime it. p The said substances will further disinfect the hides under treatment and, for instance, destroy anthrax bacilli.

Example 2. kg. of'dried leather are brought into a vat containing 200 to 250 liters of water and 0.5 kg. of one of the above named substances. It is hereby only necessary to move the Vat intermittently, for instance, for half an hour every two hours. After 24 hours the leather is thoroughly moistened and may be subjected to any treatment, such as dyeing, greasing, and the like, in aqueous fluids.

Example 5.In order to wet dry, cured, kid or alumed leather after the tanning for further treatment of the same, such leather is treated in a fulling mill or in a fulling vat containing water. To this bath 0.5 kg. of one of the above named substances is added to each 100 kg. of dried leather. The moistening will be completed during the course of two hours at most. Hereby the washing losses are very low and the addition of substances to compensate for such losses can be reduced to a minimum. The broached hides produced in this way can be easily dyed and will take up beautiful colors.

I claim:

1. A method of moistening and wetting out leather and hides, which comprises subjecting leather and hides until thoroughly moistened to treatment with an aqueous solution of the sulphonic acids of compounds which may be obtained by condensing naphthalene in the presence of condensation and oxidation agents with alcohols of the aliphatic series containing more than two carbon atoms.

2. A method of moistening and wetting out leather and hides, which comprises subjecting leather and hides until thoroughly moistened to treatment with an aqueous solution of the suphonic acids of a compound which is obtained by condensing a ring substitution product of naphthalene in the presence of condensation and oxidation agents with an alcohol of the aliphatic series containing more than two carbon atoms.

3. A method of nioistening and wetting out leather and hides, which comprises subjecting leather and hides until thoroughly moistened to treatment with an aqueous solution of a sulphonic acid of an aromatic polynuclear hydrocarbon that isalkylated in the aromatic rin f A method of moistening and wetting out leather, which comprises subjecting leather and hides until thoroughly moistened to treatment with an aqueous solution of the sulphonic acid of propylated naphthalene.

FRIEDRICH POSPIECH. 

